Australian international defender Aan leijer joined Norwich on loan from Fulham on 2nd February 2009 until the end of the 2008/9 season.

Leijer began his career with Melbourne Knights before finding success with Melbourne Victory where they won the A-League and he was named Young Player of the Year in 2006/7. He joined Fulham in August 2007 but has yet to break through to Roy Hodgson's first team. He consistently played for the Fulham FC reserve team throughout the 2007/2008 season and was also included in the squads to face both Liverpool and Reading, but stayed on the bench both times. Although tipped by Fulham reserve coach Billy McKinlay to make a greater impact in the first team during 2008/9, he has only made the bench once, in the Carling Cup defeat to Burnley.

A permanent fixture for Australia at both under-20 and under-23 levels, he has since been capped at full international level, against Singapore in March last year.

“Adrian is someone who Ian Crook has worked with during Adrian's time with Australia under-20s,” Bryan Gunn told City's official website.“I have seen him playing for Fulham reserves and together with David Carney he will provide us with extra cover - I am delighted to have him on board for the remainder of the season.”

Adrian made a total of 4 appearances and could not assist Norwich in avoiding relegation to League One

Adrian returned to Australia on 21st August 2009, rejoining Melbourne Victory for an undisclosed fee. In his first season, he scored in the Australian A-League final for Melbourne Victory to draw level against Sydney but Sydney went on to win 4-2 on penalties.

On 25th February 2015, he signed for Chinese super-league team Chongqing Lifan. He had made 135 league appearances for the Victory.

On 2nd February 2016, he moved to South Korea to sign for K-League Classic side Suwon FC.

Leijer retired from football in January 2019 to take up a position with Adidas. however in the 2019 mid-season transfer window he signed for Dandenong City of the National Premier League Victoria.